Trait UnwrapThrowExt

pub trait UnwrapThrowExt<T>: Sized {
    // Required method
    fn expect_throw(self, message: &str) -> T;

    // Provided method
    fn unwrap_throw(self) -> T { ... }
}

An extension trait for Option<T> and Result<T, E> for unwrapping the T value, or throwing a JS error if it is not available.

These methods should have a smaller code size footprint than the normal Option::unwrap and Option::expect methods, but they are specific to working with Wasm and JS.

On non-wasm32 targets, defaults to the normal unwrap/expect calls.

Example

use wasm_bindgen::prelude::*;

// If the value is `Option::Some` or `Result::Ok`, then we just get the
// contained `T` value.
let x = Some(42);
assert_eq!(x.unwrap_throw(), 42);

let y: Option<i32> = None;

// This call would throw an error to JS!
//
//     y.unwrap_throw()
//
// And this call would throw an error to JS with a custom error message!
//
//     y.expect_throw("woopsie daisy!")

Required Methods

fn expect_throw(self, message: &str) -> T

Unwrap this container’s T value, or throw an error to JS with the given message if the T value is unavailable (e.g. an Option<T> is None).

Provided Methods

fn unwrap_throw(self) -> T

Unwrap this Option or Result, but instead of panicking on failure, throw an exception to JavaScript.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementations on Foreign Types

impl<T> UnwrapThrowExt<T> for Option<T>

fn unwrap_throw(self) -> T

fn expect_throw(self, message: &str) -> T

impl<T, E> UnwrapThrowExt<T> for Result<T, E>

where E: Debug,

fn unwrap_throw(self) -> T

fn expect_throw(self, message: &str) -> T

Implementors